The objective of this research grant is to develop a simple cannulae circulatory support system (both left and right ventricles) for patients with temporary cardiac failure unresponsive to conventional therapy (including intraaortic balloon pumping). Chronically, anesthetized, instrumented sheep have been studied without cannulae, cannulae placement without pumping and with pumping (left ventricular bypass, right ventricular bypass, and biventricular bypass) for periods beyond two weeks. Left ventricular bypass consists of withdrawal of blood via an apex cannulae to a roller pump, outflow filter, and return cannula to the thoracic aorta. A similar right ventricular bypass circuit withdraws blood from the right atrium with a return cannula to the pulmonary artery. The left ventricular and right ventricular bypass circuits are combined for biventricular bypass.